$ git clone -n https://github.com/xcp-ng-rpms/kernel.git /var/lib/mock/v8.3-incoming-8924-27873/root/chroot_tmpdir/scmroot/kernel
Cloning into '/var/lib/mock/v8.3-incoming-8924-27873/root/chroot_tmpdir/scmroot/kernel'...
$ git fetch origin 45f3648c028ad6803938f26b1a6e6d5f46bd9207:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/kernel
 * [new ref]             45f3648c028ad6803938f26b1a6e6d5f46bd9207 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 45f3648c0 Merge branch 'XS-8.3' into 8.3-import_kernel-4.19.19-8.0.42.xs8.src.rpm